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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-12-08 15:29:02 +0100
committerIngo Molnar <mingo@elte.hu>2010-12-08 20:16:31 +0100
commitc277443cfc29b1623b4923219ff0bdb48b91b589 (patch)
tree0655516f81164a42dfb06e416b54c50cac33f433 /kernel/perf_event.c
parentc079c791c5a0627fc7b752d31d72e274e0596ba8 (diff)
perf: Stop all counters on reboot
Use the reboot notifier to detach all running counters on reboot, this solves a problem with kexec where the new kernel doesn't expect running counters (rightly so). It will however decrease the coverage of the NMI watchdog. Making a kexec specific reboot notifier callback would be best, however that would require touching all notifier callback handlers as they are not properly structured to deal with new state. As a compromise, place the perf reboot notifier at the very last position in the list. Reported-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Don Zickus <dzickus@redhat.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
-rw-r--r--kernel/perf_event.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 77ad22c00b9..f9d2645b554 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -21,6 +21,7 @@
#include <linux/dcache.h>
#include <linux/percpu.h>
#include <linux/ptrace.h>
+#include <linux/reboot.h>
#include <linux/vmstat.h>
#include <linux/vmalloc.h>
#include <linux/hardirq.h>
@@ -6429,7 +6430,7 @@ static void __cpuinit perf_event_init_cpu(int cpu)
mutex_unlock(&swhash->hlist_mutex);
}
-#ifdef CONFIG_HOTPLUG_CPU
+#if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC
static void perf_pmu_rotate_stop(struct pmu *pmu)
{
struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
@@ -6483,6 +6484,26 @@ static void perf_event_exit_cpu(int cpu)
static inline void perf_event_exit_cpu(int cpu) { }
#endif
+static int
+perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu)
+ perf_event_exit_cpu(cpu);
+
+ return NOTIFY_OK;
+}
+
+/*
+ * Run the perf reboot notifier at the very last possible moment so that
+ * the generic watchdog code runs as long as possible.
+ */
+static struct notifier_block perf_reboot_notifier = {
+ .notifier_call = perf_reboot,
+ .priority = INT_MIN,
+};
+
static int __cpuinit
perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
{
@@ -6518,6 +6539,7 @@ void __init perf_event_init(void)
perf_pmu_register(&perf_task_clock);
perf_tp_register();
perf_cpu_notifier(perf_cpu_notify);
+ register_reboot_notifier(&perf_reboot_notifier);
ret = init_hw_breakpoint();
WARN(ret, "hw_breakpoint initialization failed with: %d", ret);